Sharpening arrangements



March 26, 1968 A. SCHMERMUND SHARPENING ARRANGEMENTS 2. Sheets-Sheet 1 Filed July 28, 1965 INVENTOR;

HLFRED SCHIDER m LIA D March 26, 1968 A. SCHMERMUND 3, I

SHARPENING ARRANGEMENTS Filed July 28, 1965 2 Sheets-Sheet 2 IA/VE/VTOK HLFRED SCHmERIn D 7.3 We W w HTTORA/By5 United States Patent O SHARPENING ARRANGEMENTS Alfred Schmermund, 62 Kornerstrasse,

Gevelsberg, Westphalia, Germany Filed July 28, 1965, Ser. No. 475,539 Claims priority, application Great Britain, Nov. 25, 1964, 47,832/ 64 12 Claims. (Cl. 83-174) ABSTRACT OF THE DISCLOSURE A rotary cutting device is described to cut, for example, tobacco, in which straight rotating cutting edges are inclined relative to the axis of rotation so that each cutting edge engages the tobacco progressively to obtain a slicing action rather than a chopping action. The invention provides a rotatable disc for sharpening the cutting edges while they are rotating. For ensuring that the cutting edges, notwithstanding repeated sharpening, remain straight, the sharpening disc is mounted in a lever arrangement operable by cams which are rotatable synchronously with the cutting edges so that the disc is reciprocated in the direction of the cutting edge which is being sharpened and is oscillated in a curved path transversely to the axis of rotation of the rotatable sharpening disc; means may be provided for feeding the sharpening disc towards the cutting edges.

Descriplion of invention The invention relates to arrangements for sharpening rotating cutting edges.

When cutting, for example, tobacco by means of rotatable cutters, it is desirable to sharpen the cutting edges of the cutters while the cutters and therewith their edges are rotating. It is also desirable that during its rotation, each cutting edge progressively engages the tobacco to be cut in order to obtain a slicing action rather than a chopping action. It is further desirable to employ cutters having straight cutting edges, since such cutters are less expensive to manufacture than cutters having curved cutting edges.

In order to achieve a slicing action, it has been proposed to incline each straight cutting edge relatively to the axis of rotation so that the cutting edge when rotating describes a hyperboloid of revolution. An arrangement has further been proposed for sharpening such an inclined straight cutting edge while rotating, the arrangement comprising a sharpening device movable rectilinearly at an inclination to the axis of rotation of the cutting edge, said inclination corresponding to the inclination of the cutting edge relatively to its axis of rotation.

The proposed arrangement has proved to be generally satisfactory. w

' However, if the straight cutting edge is given a comparatively great inclination relative to its axis of rotation,

it has been found that an initially straight cutting edge is liable to become curved owing to repeated sharpening.

It is an object of the present invention to provide an arrangement for sharpening a straight cutting edge while it is rotating.

It is a further object of the invention to provide such a sharpening arrangement which permits sharpening of a rotating cutting edge which is inclined to the axis of rotation.

It is a still further object of the invention to provide an arrangement for sharpening a straight, inclined rotating cutting edge without curving the initially straight cutting edge during repeated sharpening.

It is another object of the invention to provide such an 70 arrangement for sharpening a plurahty of cutting edges of a cutting device having a plurality of rotatable cutters.

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These and other objects and advantages of the invention will become apparent to those skilled in the art from the following detailed description when read in conjunction with the accompanying drawings which are given by way of example and in which:

FIG. 1 is a perspective view, partly broken away, of a specific arrangement of the invention;

FIG. 2 is an elevational view of a part of the arrangement of FIG. 1; and

FIG. 3 is a plan view seen from above of the part illustrated in FIG. 2, FIGS. 2 and 3 being on a larger scale than FIG. 1.

The arrangement illustrated comprises a base 30 provided with opposite side walls 20 having extensions 23in which a shaft 22 is rotatably mounted. A carrier 24 is fixed to the shaft 22 and carries four cutters 25 each having a rectilinear cutting edge 251. The cutting edges are inclined relative to the axis of rotation of the shaft 22, so that each cutting edge on rotation describes a hyperboloid of revolution. One end of each cutting edge 251 is rotatable along a circle of radius R, the opposite end of each cutting edge being rotatable along a circle of radius 1'. Means for displacing a disc 33 for sharpening the cutting edges 251 in a direction parallel thereto comprise two rods 1 which are arranged parallel to each cutting edge 251 when in position for sharpening and which thus are inclined to the shaft 22, the inclination corresponding to the difference between the radii R and r. The rods 1 are mounted at one end in a holder 7 and at the other end in a holder 8. The holder 7 is rotatable about a stud 5 held by a screw 12 in a guide member 4. The holder 8 is mounted on a bracket 9 fixed to a guide member 4A and is provided with a groove 5C.

In the holder 8 and the bracket 9, a stud 5A is provided which carries a roller 5B engaging the groove 5C. Thus, the guide rods 1 together with the holders 7 and 8 are mounted on the guide members 4 and 4A. The guide members 4 and 4A are displace-ably mounted on parallel guide rods 3 extending in transverse direction to the rods 1, the guide rods 3 being fixed on arms 2 which by means of bushings 21 are rotatable about the shaft 22, and thus the guide members 4 and 4A together with the holders 7 and 8 are rotatable about the shaft 22. The arms 2 are of equal length, and are connected to operating rods 31, 32 which are linked to arms 62 mounted on a shaft 27 by means of hubs 66. One of the arms 62 is provided with a roller arm 63 carrying a roller 64 which co-operates with ,a cam mounted on a control shaft 28. By means of the cam 65 the arms 2 and thereby the rods 1 with the sharpening disc 33 are rotatable about the shaft 22.

The guide member 4 carries a guide link 11, and the guide member 4A carries a similar guide link 10. The guide links 10 and 11 are'each provided with a roller 13 rectilinearly movable in a stationary slot 14 provided in a bracket 15, each bracket 15 being fixed at its lower end 16 to a traverse 17 by means of angular pieces 18 and 19, the traverse 17 being mounted on the sidewalls 20. The other end of each bracket 15 is fixed on a stationary part (not shown) of the machine.

The holder 8 has an extension 8A which carries a toothed wheel 42. On the holder 7, holding arms 51A and 51B are provided which comprise bearings 51, 51C, 48 and 49 in which shafts 50 and 47 are mounted which are angularly inclined to each other.

' On the shaft 47 a toothed wheel 44 and a bevel gear wheel 45 are mounted. A toothed driving belt 43' is trained around the toothed wheels 42 and 44. On the shaft 50, a pinion 53 and a further bevel gear wheel 46 are mounted, the further bevel gear wheel 46 meshing with the bevel gear wheel 45. The bearing 51C has a cylindrical extension on which guides 55 and a holder 52 for the guides 55 are rotatably provided. A rack 54 is mounted in the guides 55 and meshes with the pinion 53. At one end, the rack 54 carries a clamp 56, a projection 58 of which is pivoted to an arm 57 which has a hub 67 rotatably mounted on the shaft 27 and secured against axial displacement by retaining rings 68. The arm 57 has a roller arm 59 carrying a roller 60 co-operating with a cam 61 rotatable by the control shaft 28. The control shaft 28 and the shaft 27 are mounted in portions 69 of the side walls 20 and are additionally supported by a support wall 29.

A guide member 37 for the sharpening disc 33 is slidably mounted on the rods 1 and carries an angular member 40 to which the driving belt 43 for displacing the guide member 37 is fixed by means of a clamp 41. The guide member 37 is also provided with a transverse guide 38 on which a feed slide 39 is displaceable. On the feed slide 39 a motor 34 is mounted for rotating the sharpening disc 33 fixed thereto by means of a nut 35.

A tobacco rod to be cut is indicated by reference numeral 26. The width of the carrier 24 for the cutters 25 equals approximately the length L of the cutters 25 which in turn approximately equals the width of the tobacco rod 26. AA indicates a line passing through the centre of pivots connecting the operating rods 31, 32 to the arms 2. The distance s is indicative of the inclination of the cutting edge 251 relative to the axis of rotation of the carrier 24.

B--B indicates a line which connects the points of contact between the sharpening disc 33 and a cutting edge 251 when the sharpening disc 33 is in its uppermost position. a indicates an angle through which the sharpening disc 33 can be turned upwards from a centre position; the sharpening disc 33 can be turned downwards by an equal angle so that the total angle of oscillations of the sharpening disc 33 amounts to 20c and is determined by the shape of the cam 65.

While the sharpening disc 33 is oscillated through the angle of 211 by the cam 65, the slide 39 is reciprocatcd by means of the cam 61, rollers 60, the roller arm 59, the arm 57, the clamp 56 with its projection 58, the rack 54, the pinion 53, the shaft 50, the bevel gear wheels 46 and 45, the toothed wheel 44, the belt 43, the angular member 40 and the clamp 41. While the sharpening disc 33 oscillates, the bearing 52 with the rack guides 55 follows the oscillations on the projections of the bearing 51C. This is enabled by the projection 58 forming a pivot and the rollers 13 being movable in the slots 14, so that the entire sharpening mechanism is moved by means of the guide members 4A in the transverse direction along the guide rods 3.

The feed of the sharpening disc 33 to the cutting edges 251 is effected by means of the transverse guide 38 and the feed slide 39 in known manner. The reciprocating and oscillating movements are controlled in timed relationship by the cams 61 and 65 which are jointly rotatable by the control shaft 28 which is driven by any suitable drive which also drives the shaft 22 for rotating the cutters 25. The cams 61 and 65 are shaped and keyed to the control shaft 28 in such a manner that during sharpening a line connecting the centre of the sharpening disc 33 to the instantaneous point of contact between the sharpening disc 33 and the rotating cutting edge 251 which is just being sharpened passes through the axis of the shaft 22, that is to say through the axis of rotation of the cutting edge 251.

When this condition has been met the cutting edges will not be curved by repeated sharpening. It will be recognized that'apart'from the feed movement of the sharpening disc, areciprocating movement of the same parallel to the cutting edges is required so that the cutting edge can be sharpened along its entire length. Furthermore, without the oscillatory movement the said connecting line would not, at any instant, pass through the said axis and therefore an irregular shape would be obtained for the cutting edge.

It should be clearly understood that the arrangement described and illustrated is given by way of example only. In fact, modifications, omissions and additions are possible without departing from the spirit of this invention.

I claim:

1. An arrangement for sharpening a rotatable straight cutting edge while rotating, comprising a rotatable carrier, at least one cutter attached to said carrier for rotation therewith, said cutter having a straight cutting edge inclined relative to the axis of rotation of said carrier so as to describe, when rotating, a surface of revolution of second order, a rotatable disc for sharpening said cutting edge while rotating, means for reciprocating said disc rectilinearly in the direction of said cutting edge while being sharpened, means for oscillating said disc in a curved path transversely to its own axis of rotation, and means for feeding said disc towards said cutting edge.

2. An arrangement as defined in claim 1, wherein a plurality of cutters are attached to said carrier.

3. An arrangement as defined in claim 1, and further comprising an electric motor for rotating said disc, said motor having a rotatable shaft carrying said disc.

4. An arrangement as defined in claim 3, wherein said feeding means comprise a feed slide on which said motor is mounted, and means for guiding said feed slide in a direction transverse to the axis of rotation of said disc.

5. An arrangement as defined in claim 1, wherein said feeding means comprise a feed slide carrying said disc, and means for guiding said feed slide in a direction transverse to the axis of rotation of said disc.

6. An arrangement as defined in claim 5, wherein said reciprocating means comprise a toothed driving belt, gear means meshing with said toothed driving belt, means for alternatingly rotating said gear means in opposite senses, thereby reciprocating said toothed driving belt, and means for fixing said guiding means to said driving belt.

7. An arrangement as defined in claim 1, wherein said reciprocating means comprise a toothed driving belt, gear means meshing with said toothed driving belt, means for alternately rotating said gear means in opposite senses, thereby reciprocating said toothed driving belt, and means for linking said disc to said belt.

8. An arrangement as defined in claim 7, wherein said means for alternately rotating said gear means in opposite senses comprise a rotatable cam, a follower co-operating I with said cam, a rack, linking means between said follower and said rack to reciprocate said rack, and means operatively connecting said rack to said gear means.

9. An arrangement as defined in claim 8, wherein said oscillating means comprise a second rotatable cam, a second follower co-operating with said second cam, a linkage between said follower and said disc for oscillating the same, said arrangement further comprising a rotatable shaft, said cam and said further cam being keyed to said shaft for joint rotation, whereby the operation of said reciprocating means is correlated to the operation of said oscillating means.

10. An arrangement as defined in claim 1, wherein said oscillating means comprise. a rotatable cam, a follower co-operating with said cam, and a linkage between said follower and said disc for oscillating the same.

11. An arrangement as defined in claim :10, wherein said linkage comprises a first shaft, a first arm connected to said follower and oscillatable about said shaft, a sec ond arm connected to said first arm and oscillatable about said shaft, 21 second shaft, a rod pivoted to said second arm, a third arm pivoted to said rod and oscillatable about said second shaft, and a carrier rod carrying said disc and connected to said third arm.

12. A tobacco cutting arrangement comprising a rotatable carrier, at least one cutter attached to said carrier for rotation therewith, said cutter having a straight cutting edge inclined relative to the axis of rotation of said carrier so as to describe, when rotating, a surface of revolution of second order, a rotatable disc for sharpening 5 6 said cutting edge while rotating, the axis of rotation of References Cited said disc being substantially parallel to said cutting edge UNITED STATES PATENTS while being sharpened, means for reciprocating sa1d dlsc rectilinearly in the direction of its own axis of rotation, 1,149,255 8/1915 GlantZ 51249 means for oscillating said disc in a curved path trans- 5 3,144,063 8/ 1964 Schmermlmd 146117 versely to its own axis of rotation, and means for feeding said disc towards said cutting edge. ANDREW R. J UHASZ, Primary Examiner. 

